Deployment is the moment when code stops being a developer’s problem and becomes everyone’s. It is the act of taking something that worked on a build server and putting it in front of real users, on real infrastructure, and handling real traffic. For a long time, this moment was riskier than it had any reason to be, and the strategies we will discuss in this article are what teams built to take that risk down.

Several distinct strategies are in common use today, and each one is an answer to a specific problem that the previous approaches couldn’t solve well enough. Some reduce the blast radius (the number of users affected) when a deploy goes wrong. Others separate the moment the code reaches production from the moment users actually see it.

In this article, we’ll go through the main deployment strategies used in production today, looking at how each one works, what it costs, and when it makes sense to use.